Railway brake mechanism



Jan. 24, 1961 K. A. BROWNE ET AL RAILWAY BRAKE MECHANISM 6 Sheets-Sheet 1 Filed Sept. 10, 1958 J. JENNA/4am? BY GEORGE Jan. 24, 1961 K. A. BROWN-E ETAL 2,969,129

RAILWAY BRAKE MECHANISM 6 Sheets-Sheet 2 Filed Sept. 10, 1958 INVENTORJ K/ENNETH A- 5R0 w:

mm Mm mu 6:046: JSE/vMvAI/sE/P flrraRNE/S Jan. 24, 1961 K. A. BROWNE ET AL 2,969,129

RAILWAY BRAKE MECHANISM 6 Sheets-Sheet 3 Filed Sept. 10, 1958 INVENTOS fiEN/VEIWA fikawms BY GEORGE J- Jan. 24, 1961 K. A. BROWNE ET AL, 2,969,129

RAILWAY BRAKE MECHANISM Filed Sept. 10, 1958 6 Sheets-Sheet 4 h mk INVENTORS KEN/v61?! A 820 WNE v8 8 0% w m mm R m9 BY 65am: .fsawv/musew Jan. 24, 1961 K. A. BROWNE ET AL 2,969,129v

RAILWAY BRAKE MECHANISM Filed Sept. 10, 1958 6 Sheets-Sheet 5 United States Patent RAILWAY BRAKE MECHANISM Kenneth A. Browne, Lakewood, and George J. Sennhauser, Par-ma, Ohio, assignors to The Chesapeake and Ohio Railway Company, Cleveland, Ohio, a corporation of Virginia Filed Sept. 19, 1958, Ser. No. 760,237

25 Claims. (Cl. 188-333) This invention relates to vehicle braking apparatus and, as one of its objects, aims to provide novel brake mechanism of a simple and practical form suitable for use on vehicles of the convertible road-rail type and which will be operable in a compatible relation with conventional pneumatic railway brake mechanisms in response to predetermined brake pipe pressure variations initiated from a control vehicle or locomotive.

Another object is to provide novel railway brake mechanism comprising a brake cylinder having a spring means therein operable to supply a brake-applying force and a fluid pressure responsive actuator device for supplying brake-releasing force and wherein transmission means, preferably a force amplifying lever means, transmits the brake-releasing force to the brake cylinder in opposition to the spring means of the latter.

A further object is to provide novel brake mechanism of the kind above indicated and having manually operable brake releasing means for supplying the brake-releasing force in opposition to the spring means, such manually operable releasing means preferably comprising lever means eifective through the force transmission means associated with the brake cylinder and actuator device.

Still another object is to provide novel brake mechanism of the kind comprising a brake cylinder and in which the brake-applying and brake-releasing forces are supplied respectively by a spring means and a fluid pressure responsive means, and wherein an automatic slack adjusting means is incorporated in the brake cylinder.

It is also an object of this invention to provide novel brake mechanism of the kind indicated above and Wherein the brake cylinder comprises a cylinder member having a rod means operable therein and is connected between a brake beam carrying a brake shoe and a projecting means of the journal box of a running gear, the cylinder member preferably being carried by the brake beam.

Additionally, this invention relates to brake mechanism of the kind comprising a brake shoe supported by a brake beam or the like as a carrier, and provides novel means for detachably mounting the brake shoe on the carrier for quick and easy replacement.

Other objects and advantages of this invention will be apparent in the following detailed description and in the accompanying drawings forming a part of this specification and in which:

Fig. 1 is a side elevation, with portions in section, of the wheel suspension or running gear of a road-rail type of vehicle and showing the brake mechanism of the present invention applied to the rail wheels of the vehicle;

Fig. 2 is a partial plan view of the brake mechanism showing the brake beam and the brake cylinder device in association with a rail wheel, the view being partially diagrammatic;

Fig. 3 is an elevation of the brake mechanism of Fig. 2 but with the vehicle wheel and certain other structure omitted and with certain portions shown in section;

Fig. 4 is a plan view corresponding with a portion of Fig. 2 and showing the brake cylinder device and the associated parts on a larger scale;

Fig. 5 is mainly an elevational view corresponding with a portion of Fig. 3 and showing the brake cylinder device on a larger scale;

Fig. 6 is a sectional view taken through a brake shoe and the mounting means therefor, as indicated by section line d6 of Fig. 3;

Fig. 7 is a side elevation corresponding with a portion of Fig. 1 and showing the brake cylinder device in detached relation and on a larger scale;

Fig. 8 is a sectional view taken through the brake cylinder axially thereof as indicated by section line 88 of Fig. 7;

Fig. 9 is a partial axial sectional view corresponding with a portion of Fig. 8 and showing certain components of the slack adjusting means on a large scale;

Fig. 10 is a plan view showing one of the levers associated with the brake cylinder in a detached relation;

Fig. 11 is a plan view showing another such lever in detached relation;

Fig. 12 is a side elevation showing the thrust member of the slack adjusting means in detached relation;

Fig. 13 is a perspective view showing a pivot shaft of the slack adjusting means in detached relation;

Fig. 14 is a axial section taken through a compatibility valve of the mechanism and showing such valve on an enlarged scale; and

Fig. 15 is a diagram showing a comparison of force as a graphic illustration of the functioning of the compatibility valve of Fig, 14.

The brake mechanism 10 of the present invention is shown in Fig. 1 as applied to a vehicle 11 of the convertible road-rail type having a pair of road wheels 12 and a pair of rail Wheels 13. The road-rail vehicle 11 is more fully disclosed in copending patent application Serial No. 548,602 filed November 23, 1955, now Patent 2,889,785 issued June 9, 1959, with which this application is related through common ownership. For the purposes of the present invention, the vehicle 11 is represented primarily by the wheel suspension 15 of which the road wheels and rail wheels 12 and 13 form a part. The brake mechanism 1% is shown as being associated with the rail wheels 13 of the wheel suspension 15.

In addition to the road wheels and rail wheels 12 and 13 the wheel suspension 15 also comprises a torsion spring means 16, with which frame and strut portions 17 and 18 of the vehicle 11 are connected, and pairs of road wheel and rail wheel arms 19 and 20 projecting from such torsion spring means. The road wheel arms 19 project from the torsion spring means 16 in a forward direction from the axis 22 of the latter and have the road Wheels 12 mounted thereon. The rail wheel arms 20 project from the torsion spring means 16 in a rearward direction from the axis 22 and have the rail wheels 13 mounted thereon as by means of suitable hanger bars 23.

The road wheel arms and rail wheel arms 19 and 20 are swingable about the axis 22 for selectively moving the road Wheels 12 and the rail wheels 13 to and from a lowered or load-carrying position. In Fig. 1 of the drawings, the Wheel suspension 15 is shown with the rail wheels 13 in such a load-carrying position in engagement with rails 25 of a conventional railroad track.

For causing such selective swinging of the road wheels and rail wheels to elevated or lowered positions, an actuating lever 26 is provided and is connected with the arms 19 and 2t through the torsion spring means 16. The upper or free end of the lever 26 carries-a trunnioned nut 27 with which a drive screw 2% co-operates. The screw 28 is rotatably driven by a power device 29 comprising a suitable reversible motor mounted on the frame portion 17.

The rail wheels 13 and the rail wheel arms 20 form a part of a railway running gear 3t) with which the brake mechanism It) is associated. The rail wheels 13 are of a conventional form and include an axle 31 and a journal portion 32 extending into a journal box 33. The running gear 30 also includes a shaft portion 35 or anchorage projection projecting from the journal box 33 on the outer side thereof, that is on the side thereof remote from the rail wheel 13, and with which the brake mechanism co-operates in a manner to be explained hereinafter. The shaft portion 35 is preferably a projection on the journal box cover 33a although, if desired, it could be formed as a projection of the journal 32.

The brake mechanism 10 comprises a brake beam 36 located in front of the rail wheels 13 and supporting brake shoes 37 for braking co-operation with such Wheels. The brake mechanism 10 also comprises brake cylinder devices 38 located on the outer ends of the brake beam 36 and connected with the shaft portions 35 projecting from the journal box covers 33a. As will be explained in greater detail hereinafter, the brake cylinder devices 38 are reactively effective between the shaft portions 35 and the brake beam 36 for supplying brakeapplying and brake-releasing forces and movements to the brake shoes 37 through the brake beam.

The brake mechanism 10 also includes a valve device 40 which has been conveniently referred to herein as a relay valve or compatibility valve and which is shown more or less diagrammatically in Fig. 2 of the drawings and in greater detail in Fig. 14. As will be further explained hereinafter, the valve device 4% renders the brake mechanism 10 usable in a compatible relation with conventional pneumatic brake mechanisms located on conventional railway cars, such as with the well-known AB type of brake mechanisms and control valves, and which renders the subject brake mechanism 10 operably responsive to brake pipe pressure variations initiated from a control vehicle or locomotive.

The brake beam 36 is a rigid member, in this case a hollow member, extending crosswise of the vehicle 11 in front of the rail wheels 13 and suspended in this relation by suitable hanger rods 41. The brake beam has outwardly and rearwardly curved end portions 42 on which the brake cylinder devices 38 are mounted and, at points adjacent the rail wheels 13, is provided with mounting devices 43 for detachably mounting the brake shoes 37 thereon. Since the brake cylinder devices 38 and the brake shoe mounting devices 43 are of the same construction for both sides of the vehicle, only the devices on one side need be described in detail.

As shown in Figs. 2, 3 and 6, the brake shoe mounting device 43 comprises a bracket 44 formed by spaced vertical plate members 44 and 44 secured to the brake beam 36, as by welding, and a curved mounting plate 45 secured to the edges of the spaced plate members and having the concave side thereof presented toward the rail wheel 13. The mounting device 43 also comprises releasable locking means 46 for the shoe 37 and which will be described presently.

The brake shoe 37 is here shown as comprising a backing portion in the form of a curved metal plate 47, and a body portion 48 formed of suitable friction material and secured to the backing plate 47 as by being molded thereon. The body portion 48 is of a curved shape for frictional co-operation with the periphery of the tire portion of the rail wheel 13 and preferably comprises a composition having a high coeflicient of friction. The backing plate 47 has substantially the same curvature as the mounting plate 45 and has its convex outer side lying against the concave side of the mounting plate when the brake shoe 37 is mounted on the support device 43 as shown in Fig. 6.

When the friction material comprising the body portion 48 of the brake shoe 37 becomes worn, replacement of the shoe becomes necessary and, in accordance with one feature of the present invention, the mounting device 43 is of a construction to facilitate the removal of the worn shoe and the substitution of a new shoe therefor. The mounting plate 45 of the mounting device 43 is accordingly provided at the lower and upper ends thereof with stationary and movable locking members 59 and 51 which are of a hook-like shape, as shown in Fig. 6, and are in holding engagement with the backing plate 47 of the shoe.

The lower locking member 50 is attached to the mounting plate 45 by a weld 52 and engages in a recess 53 of the lower end or flange of the backing plate 47 of the brake shoe. The upper locking member 51 extends through a notch 54 provided in the upper end of the mounting plate 45 and is engaged in a recess 55 provided in the upper end or flange of the backing plate 47. The engagement of the lower and upper locking members 59 and 51 in the associated recesses 53 and 55 of the backing plate 47 of the brake shoe provide a holding effect on the latter by which the shoe is held against sidewise shifting relative to the mounting plate 45.

The notch 54 of the mounting plate 45 forms a guideway for the movable locking member 51 and in which guideway this locking member is movable in opposite directions toward and away from the lower locking member 50 for locking or releasing the brake shoe 37. The movable locking member 51 is carried by a push-pull actuating member 57 which is here shown as being in the form of a resiliently flexible or semirigid strap lying against or adjacent the rear surface of the mounting plate 45 and having a loop portion 58 on the lower or free end thereof. Movement in the locking and releasing directions is transmitted to the locking member 51 through the actuating member 57 and, for this purpose, the mounting device 43 is provided with an actuating shaft 60 having an eccentric portion 61 embraced by the loop portion 58 as shown in Fig. 6.

The actuating shaft 60 has the inner end thereof pivotally mounted in the plate members 44 and 44 of the mounting device 43, as shown in Figs. 3 and 6, with the eccentric portion 61 of this shaft lying between the pair of plate members. The outer end of the actuating shaft 60 is pivotally supported by a bracket or hanger 62 depending from the brake cylinder device 38 and is provided with an eye portion 63. The shaft 64 is also provided with an actuating arm, preferably a crank 64, formed by a bent portion of the shaft and lying adjacent the plate member 44 of the mounting device 43. A tension spring 65 having one end thereof anchored in a slot 66 of the plate member 44 has its other end connected with the crank 64 by means of a hook por tion 67.

Rotation of the eccentric portion 61 in the loop portion 58 by a pivotal movement of the actuating shaft 69 causes the actuating member 57 to transmit locking and releasing movements to the movable locking member 51 in the manner of a push-pull connecting rod. The angular relation between the eccentric portion 61 and the crank 64 is such that the spring 65 constantly tends to rotate the shaft 6%) in a direction which will result in the eccentric portion applying a pulling force to the actuating member 57 to thereby normally maintain the locking member 51 in its locking position. The actuating shaft 6% can be rotated manually in opposition to the spring 65 by applying torque to the eye portion 63 and, to facilitate such manual operation, a suitable bar or leverlike handle can be inserted through the opening of the eye portion.

The brake cylinder device 38 will be described next. This device is shown in the drawings as comprising a brake cylinder 70 having rod means 71 operable therein and projecting therefrom, and an actuator or brakereleasing cylinder 72 having piston means 73 operable therein and including a piston rod 74 projecting from such actuator cylinder. The brake cylinder device 38 also includes a force and motion transmitting means 75 comdeca es prising levers 68 and 69 and which is eilective to transmit brake releasing force from the piston rod 74 of the actuator cylinder 72 to the brake cylinder 70, as will be explained hereinafter. Additionally, the brake cylinder device 38 comprises a manually operable brake releasing means which is here shown in the form of a lever 76 and which will likewise be described hereinafter.

The brake cylinder 70 and the actuator cylinder 72 are connected together to form a cylinder unit or assembly 73 which is here shown as being rigidly mounted on the curved outer end portion 42 of the brake beam 36, as by being welded thereto. The connection of the cylinder unit 78 with the outer end of the brake beam 36 could be of a form to provide a desired degree of flexibility therebetween. This cylinder unit 78'includes a pair of spaced connecting plates or brackets 80 and 81 which are formed integral with or connected to the cylinder head 82 of the brake cylinder 70 and which plates support the actuator cylinder 72. The actuator cylinder 72 has a head 83 secured therein by screws 34 and which head has studs 85 projecting therefrom.

The cylinder head 82 of the brake cylinder 71 is provided with a sleeve portion 36 which forms a bearing for the rod means 71 and the connecting plates 8% and 31 have their lower edges secured to this sleeve along opposite sides there-o-f as by means of welds 87. The upper ends of the connecting plates 80 and 31 are provided with eye portions 88 through which the connecting studs 85 of the cylinder head 83 extend. The connecting plates 8i and 81 are also provided adjacent the upper ends thereof with rollers 9i and 91 with which the brake releasing lever 76 co-operates in a manner to be explained hereinafter. The rolls 9!) and 91 are rotatably supported by shoulders pivot shafts 92 which are mounted on the connecting plates 80 and 81, as by being welded into openings 93 of these plates.

The brake cylinder 70 is provided with a cylinder chamber or bore 95 into which one end of the guide sleeve 86 projects and which contains a compression spring 96 disposed in surrounding relation to such one end of the guide sleeve. The compression spring 96 produces the brake applying force which is transmitted to the brake shoe 37 through the cylinder unit 78 and the brake beam 36 as will be further explained hereinafter. The outer end of the brake cylinder 70 is provided with a cover 97 which is removably held in place by retaining bolts 98 and is also provided with an internal ring 99 located in the bore 95 and engageable by the outer end of the spring 96 as a stop ring or abutment ring. The abutment ring 99 is removably mounted in the cylinder bore 95 by means of a snap ring 1% engaged in an internal groove of the cylinder wall.

The rod means '71 comprises a hollow piston rod 162 slidable in the guide sleeve 86 and a pair of co-operating screw and nut members 1% and 1114 located in the hollow piston rod and extending coaxially thereof. The inner end of the piston rod 11132. carries an annular abutment flange 101 and the nut 164 has an annular abutment shoulder 1115 in engagement with such flange on one side of the latter. The screw member 163 is formed by a threaded portion of a brake rod 1% whose plain or unthreaded port-ion is of a substantial length and projects fro-m the hollow piston rod M2. The nut 1M and the screw portion 163 with which it co-operates form a part of an automatic slack adjusting mechanism 167 which is located in the brake cylinder 7% and which will be further described hereinafter.

To facilitate the relative sliding movement between the guide sleeve 86 and the piston rod 1132 the guide sleeve is provided with axially spaced bushings 16:9 and 110. The inner end of the piston rod 192 co-operates with the spring 96 through a cup-shaped spring seat 111 which is' mounted on such inner end by having an end wall or internal flange 112 in engagement with the other side of. the abutment flange 101. The spring seat 111 6. is telescope'd into the spring 96' coaxially thereof; as shown in Fig. 8, and includes an external annular abutment flange 113 against which the outer end of the spring is seated. The other end of the spring'96 seats against the cylinder head 82.

The projecting end of the brake rod 106 is provided with a transverse bearing sleeve 115 which includes a bushing 116 of a suitable material, preferably plastic or resilient in character, and which bearing sleeve is mounted on the projecting shaft portion 35 of the journal box 33. The bearing sleeve 115 can be retained on the shaft por tion 35 as by means of a suitable retaining collar or washer 117 and an associated transverse retaining pin 118.

The connection of the outer end of the brake rod 106 with the shaft portion 35 provides an anchorage. for the brake cylinder device 38 on the running gear 30 of the vehicle 11 and against which anchorage the compression spring 96 can react through the spring seat 111 and the brake rod 106 for applying the brake actuating force and mvoement to the cylinder head 82 of the brake cylinder 711 for transmission to the brake shoe 37 through the brake beam 36.

As shown in Figs. 7 and 8, the piston rod 102 is provided with a pair of trunnions 120 and 121 for form ing a fulcrum connection between the transmission means 75 and the rod means 71. The trunnions 120 and 121 are carried by a trunnion member 122 which is attached to the outer end of the piston rod 102 by means of a threaded connection 123. The trunnion member 122 also forms a bearing which is slidable on the plain stem portion of the brake rod 106 during relative axial adjusting movements between the brake rod and the piston rod.

The actuator cylinder 72 is a single-acting cylinder having a bore 125 in which the piston 73 is reciprocably operable. The end portion 125 of the cylinder bore formsa pressure fluid chamber to which actuating fluid, such as brake pipe pressure, can be supplied through a pipe 126. The piston rod 74 of the actuator cylinder 72 is slidable in the cylinder cover 33 and projects from the latter between the pair of attaching studs 85. Movement of the piston 73 and its projecting rod 74 toward the right as seen in Fig. 7, in response to fluid pressure supplied to the cylinder chamber 125 produces brake releasing force and motion for use in releasing the brake in opposition to the brake applying force of the spring 96.

As has been indicated above, the transmission means 75 comprises levers 68 and 69 of which the lever 68 can 'be conveniently referred to as a brake lever and the lever 69 can be designated a thrust lever. The brake lever 68 is mounted on the trunnions 120 and 121 of the piston rod 102 of the brake cylinder 70. As shown in Figs. 5 and 10, the intermediate portion of the brake lever 68 is formed by spaced sides or arms 1-27 and 123 carrying bearing bosses 129 and 130 which are fitted with a pair of antifriction bearings 131 and 132 by which this lever is rockably mounted on the trunnions 120 and 121. The space between the sides 127 and 128 provides a through opening or passage 133 through which the rod means 71 extends. The antifriction bearings 131 and 132 are retained in the bosses 129 and 130 by suitable snap rings 134.

The brake lever 63 is provided with a power input end 136 and a power output end 137. The power input end is connected with and swingable by the outer end of the piston rod 74 of the actuator cylinder 72. For this purpose, the brake lever 63 is provided with an eye portion 139 which is received in a forked end 1400f the piston rod '74 and is connected with the latter by a transverse pivot pin 141. For a purpose which will appear hereinafter, the pivot pin 141 is of a length to provide shaft projections 142 and 143 extending in opposite directions ondo pposite sides of the forked portion of the piston to 4.

The thrust lever 69 is a substantially flat plate as shown in Figs. 5, 7, and 11 of the drawings and, at one end thereof, has a rounded edge 145 rockably seated in the recess of a channel-shaped seat 146 which is welded or otherwise secured on the cylinder head 82 of the brake cylinder 70. Adjacent the outer or swingable end thereof, the thrust lever 69 is provided with a pair of notches 147 in the side edges thereof. The power output end 137 of the brake lever 66 is a forked end having a pair of hook-shaped elements 137 engaged in the notches 147 of the thrust lever.

At an intermediate point thereof, the thrust lever 69 cooperates with a keeper 149 which is fixed on the sleeve 86 and projects through a circular hole 149 provided in this lever. The keeper 149 retains the lever 6% in engagement with the seat 146 but a limited amount of shifting of the lever relative to the keeper is permitted by making the hole 149 of larger diameter than the keeper and by providing the keeper with flats on the sides thereof as shown in Fig. 7.

From the construction and arrangement provided for the brake cylinder 76, the actuator cylinder 72 and the power transfer means 75, as described above, it will now be recognized that the compression spring 66 acts continuously against the abutment flange 113 of the spring seat 111 and against the cylinder head 82 so as to tend to move the brake cylinder 76 toward the shaft portion 35 to thereby impart a translatory brake-applying movement to the brake beam 36 for pressing the brake shoe 37 into braking co-operation with the rail wheel 13.

It will likewise be recognized that when brake pipe pressure fluid of a suitable pressure value is supplied to the chamber 125 of the actuator cylinder 72, it will move the plunger 73 toward the right to cause clockwise swinging of the brake lever 68, as seen in Fig. 7, to thereby transmit brake-releasing force and motion from the piston rod 74 to the brake cylinder 76 through the thrust lever 69. Since the brake rod 106 is effective on the spring seat 111 through the abutment shoulder 165 of the nut 104, the spring seat will be held relatively stationary and the thrust transmitted by the lever 69 to the brake cylinder 70 will move the latter toward the left in opposition to the spring 96 to shift the shoe 37 to a released position.

The release of the fluid pressure from the cylinder chamber 125 of the actuator cylinder 72 will permit movement of the piston 73 in the opposite direction, that is toward the left as seen in Fig. 7, during which the brake lever 68 will be swung in a counterclockwise direction on the fulcrum provided by the relatively stationary brake rod 166 and the expansive action of the spring 56 will cause movement of the brake cylinder 76 toward the right to reapply the brake shoe 37 against the rail wheel 13.

The design of the power transfer means 75 of the brake mechanism is such that the lever arm valves and functioning of the levers 68 and 69, in relation to the rate of the spring 96 and the working travel of the piston 73, will cause a substantially constant brake releasing force to be applied to the brake beam 36 throughout the brake releasing travel of the latter for a given pressure valve of brake pipe fluid being supplied to the actuator cylin der 72.

The design of the brake mechanism 10 is also such that only a small expansive movement of the spring 96 will be needed to cause the full braking force to be developed for pressing the shoe 43 against the wheel 13. This is important because the force developed by the spring 96 is proportional to the elongation or expansion of the spring, and therefore, if any great amount of expansive movement of the spring were used in developing the braking force a substantial variation in vaue of the braking force would result and would be objectionable.

Inasmuch as wear will always be taking place in the mechanism 10 during the use thereof. and will cause lost motion, there willbe a tendency toward an increase in the expansive movement of the spring 96 which, if

permitted to occur beyond a given amount, would result in such a variable and undesirable brake applying force to be developed. The present invention meets this problem by providing the automatic shock adjusting means 167 in the brake cylinder 70, that is, an automatic shock adjuster in combination with a spring applied brake means so as to continuously get rid of objectionable slack and thus limit the expansive movement of the spring 96 to a small value and within which the braking force being developed will be substantially constant.

The manually operable brake releasing lever 76 is swingably mounted on the projecting shaft portions 142 and 143 of the pivot pin 141 of the piston rod 74. The lever 76 is of a forked shape, as shown in Figs. 4 and 5, and has spaced arms 151 pivoted on the respective pivot pin projections 142 and 143 with such forked end of this lever in straddling relation to the eye portion 139 of the piston rod 74. The forked end of the release lever 76 is provided with cam means comprising convexly curved cam portions 154 on the arms 151 and which cam portions are engageable with the rollers 51) and 91.

The cam portions 154 are provided with recesses 155 forming a detent means for co-operation with the rollers 96 and )1 as a releasable holding means by which the lever 76 can be maintained in a position corresponding with a released condition of the brake. A torsion spring 156 mounted on the pivot pin 141 has coiled portions 156*- and 156 located on opposite sides of the forked end 146 (see Figs. 4 and 7) and efiective on a spring seat in the form of a transverse pin or roller 151) extend-- ing between the arms 151 of the lever 76.

The brake mechanism 10 is shown in Pig. 7 in a fully released condition as a result of the action of fluid pressure in the cylinder chamber 125 of the actuator cylinder 72. The release lever 76 is also shown in Fig. 7 in its ineffective position which is with its lever arm 76 carrying the handle 76 extending in the direction of the axis of the piston rod 7 4-. At this time, the cam portions 154 are disengaged from the rolers an and @1.

When the brake is in the applied condition, the cam portions 154 will be close to, or in engagement with, the rollers and M such that manual swinging of the release lever 76 in a counterclockwise direction as seen in Fig. 7 will cause the cam portions to react against the rollers thereby causing a pulling force to be applied to the piston rod 74 and the same manner of clockwise swinging to be imparted to the brake lever 68 as when the brake lever is swung by a fluid pressure actuation of the piston 73. The clockwise swinging of the brake lever 68 by the manual actuation of the release lever 76 thereby causes a brake-releasing force and movement to be applied to the brake cylinder 76 in opposition to the spring 96.

When the extent of the brake-releasing swinging move ment applied to the lever 76 bring the recesses 155 of the cam portions 154 into co-operation with the rollers 91 and 91, the rollers will be effective in such recesses as a holding means for releasably maintaining the brake in a released condition so long as pressure fluid is not being supplied to the actuator cylinder 72. Manual swinging applied to the release lever 76 in an opposite or clockwise direction will disengage the recesses 155 from the rollers, whereupon the rollers wi'l move relatively of the cam portions 154 in a downhill direction thereon thereby permitting swinging of the brake lever 68 in a direction to allow the spring 96 to reapply the brake.

The holding cooperation between the rollers 90, 91 and the recesses 155 of the lever '76, in relation to the force of the torsion spring 156, is such that wherever fluid pressure is supplied to the chamber of the actuator cylinder 72 to actuate the piston 73, the recesses will be sufiiciently disengaged from the rollers to permit the torsion spring to swing the lever 76 to its brake releasing position. Thus, even though the lever 76 is left standmg in a position with its recesses engaged by the 9 rollers 90 and 91, the torsion spring 156 will automatically return the lever to its Fig. 7 position upon the occurrence of the next fiuid pressure actuation of the piston 73.

The slack adjusting mechanism 107 (see Fig. 8) comprises, in addition to the nut member 104 and the screw portion 103, a thrust member or reaction member 157 mounted on the cover 97 of the brake cylinder 70 and extendng into the chamber 95 of the latter. This reaction member 157 is mounted on the cylinder cover 97 by having a stem portion 157 slidable in a bushing 158 which is suitably mounted in an opening of the cover, as by means of a threaded connection therewith. At the outer end thereof the thrust member 157 is provided with a handle or knob 159 which is secured on the stern portion 157 as by means of a transverse pin 160.

At the inner end thereof, the thrust member 157 is provided with a head portion 161 and a pair of rollers 162 located on opposite sides of the'head portion and supported by the ends 163 of a transverse pivot shaft' 163 extending through such head portion. The outer end of the stern 157 of the thrust member also has secured thereon, as by means of the transverse pin 160, a sleeve-shaped ratchet member 165 carrying an annular group of ratchet teeth 166. The bushing 158 of the cylinder cover 97 also forms a holding or detent member 167 having an annular group of locking teeth 168 of a shape for mating engagement with the teeth and intervening recesses of the ratchet member 165.

The teeth 166 of the ratchet member 165 are urged into mating engagement with the teeth 168 of the detent member 167 by means of a spring 170 disposed in the surrounding relation to the stem portion 157 The spring 170 has its opposite ends seating respectively against the inner end of the bushing 158 and the head portion 161 of the thrust member 157. A guard or sealing sleeve 169, of rubber or the like, is preferably provided and is disposed in surrounding relation to the ratchet and detent members 165 and 167 for excluding dust and other foreign matter from the annular groups of teeth thereof and from entry into the brake cylinder 70 through the bushing 158.

The nut 104 is provided with a pair of inclined or helical slots 171 in opposite sides thereof and in which the rollers 162 of the thrust member 157 are engaged and operate in a manner to be explained hereinafter. The rollers 162 are retained on the ends of the pivot shaft 163 by a retainer sleeve 172 disposed in a surrounding relation to and mounted on the slotted portion of the nut 104. The retainer sleeve 172 has a radial end flange thereon which is in engagement with the abutment shoulder 105 of the nut 104. A nut return spring 174 is disposed between the cylinder cover 97 and the radial flange 173 of the retainer sleeve 172, as shown in Fig. 8, so as to be effective on the nut 104 to urge the abutment shoulder 105 of the latter toward the flange 101 of the piston rod 102.

To accommodate the pivot shaft 163, the head portion 161 of the thrust member 157 is provided with a transverse opening 175 which, as shown in Fig. 12, has flat sides 175 and is elongated somewhat in the axial direction of the thrust member. The shaft 163 has flat sides 163': on the intermediate portion thereof, as shown in Fig. 13, and also has oppositely extending reducing tapers 163 on such intermediate portion. These shapes for the opening 175 and the shaft 163 permit the shaft to tilt or rock in the head portion 161 and this allows the rollers 162 to have a limited degree of universal movement which prevents binding or sticking of the rollers in the cam slots 171. The outer faces of the rollers 162 pref e erably have a spherical contour, as shown in Fig. 8, so that the rollers will be rockably shiftable in the retainer sleeve 172 without scraping or binding against the latter.

The positions of the parts of the brake cylinder 70' and the slack adjuster 107 as shownin Fig. 8 correspond 10 with a fully released condition of the brake and with substantially no slack in the brake mechanism 10.

From the construction and anangement described above for the slack adjusting mechanism 107 it will be seen that, during each release of the brake, the cylinder 70 and its guide sleeve 86 will be moved in opposition to the spring 96 along and relative to the brake rod 106 in a. direction away from the shaft portion 35. During such a brake releasing action, the movement of the brake cylinder 70 toward the left, as seen in Fig. 8, will carry the thrust member 157 along with it thereby applying a pulling movement to the rollers 162. The rollers will thereby be moved axially outwardly in the cam slots 171 of the nut 104.

The direction of inclination of the slots 171 in relation to the helix angle of the right hand thread of the threaded portion 103 is such that this axial outward movement of the rollers 162 will react on the nut 104 to tend to cause rotation of the latter in a direction to screw the same farther onto the brake rod 106, that is to say, a rotation of the nut in a direction to cause a shortening of the brake rod. It will be recognized that, during the brake-releasing functioning of the mechanism 10, the load to which the nut 104 is being subjected is relatively lighter than during the brake-applying functioning, and hence, the nut can be more readily rotated by the rollers.

During a brake-applying functioning of the mechanism 10, the movement of the brake cylinder 70 toward the right advances the rollers 162 toward the right in the cam slots 171 which would ordinarily tend to cause unscrewing of the nut 104 from the brake rod 106, but since the nut is under a relatively heavy load during the brake-applying functioning as indicated above, it wil. resist the unscrewing rotation thereof and the cam slots will react on the rollers to cause rotation of the thrust member 157 and the ratchet member in a clockwise direction when viewed from a position outwardly of the handle 159.

This clockwise rotation of the ratchet member 165 will reset the thrust member 157 and will establish a reaction position for the rollers along the cam slots such that, during the next brake releasing functioning, the rollers will produce the onscrewing rotation of the nut for shortening the brake rod 106 as was explained above. During the rotative action of the cam slots 171 on the rollers 162 which produces the above mentioned clockwise rotation of the thrust member 157, the latter member will also be subjected to an outward axial shifting in opposition to the spring 174 and which axial shifting will permit the ratchet teeth 166 to ride over the detent teeth 168 to a new holding position.

The length of the travel of the rollers 162 along the cam slots 171 of the nut 104- will depend upon the amount of lost motion or slack existing in the brake mechanism 10. As wear .occurs between the moving parts of the brake mechanism 10, and particularly wear of the brake shoe material 48, the amount of slack in the brake mechariismwill increase and consequently the travel of the rollers 162' along the cam slots 171 during the applying and releasing actions of the mechanism will be greater in amount. When the accumulation of slack 'in the brake mechanism 10 has increased to the extent that the axial and rotative movements of the ratchet member 165, as produced by the reaction of the rollers 162 with the cam slots 171 as explained above, is sufiicient to cause the ratchet teeth 166 to be disengaged from the detent teeth 168, the ratchet member will be advanced to the new holding position. The subsequent onscrewing rotation imparted to the nut 104 by the rollers 162, as explained above, will accordingly cause a corresponding shortening of the brake rod 106.

It will thus be understood that the functioning of the slack adjusting mechanism 107 will be such as to cause slack to' be automatically taken up during the normal 'operation of the brake mechanism In to maintain the mechanism in a satisfactory condition for efiectively pressing the brake shoe 37 against the rail wheel 13 regardless of wear conditions in the mechanism. When the wear on the brake shoe material 48 has decreased the thickness of this material to a point where the brake :shoe needs to be replaced, this can be readily done by manipulation of the brake shoe locking mechanism 46 already described above and by a repositioning of the nut 184 on the brake rod 106 to enable the brake shoe mounting device 43 to accommodate the new shoe.

The repositioning of the nut 104 is accomplished by a manual rotation of the knob 159 whereby the nut can be unscrewed along the brake rod lilo to a new starting position for subsequent automatic slack adjusting rotative movements of the nut. The symmetrical form and axially straight shape of the teeth of the tooth groups 166 and 165% will permit this resetting rotation of the knob 159 when the latter is retracted in opposition to the spring 176*.

The valve device as referred to above as a compatibility or relay valve will now be described. This valve device is shown in Fig. 14 as having a housing 180 which is provided with an intake chamber 181 and an outlet chamber 182. The intake and outlet chambers 181 and 182 are separated by a pair of flexible diaphragms 183 and 134 which are clamped between connected sections 1891* and 13t of the housing. The intake chamber 1&1 is connected with the brake pipe 179 of the vehicle to receive pressure fluid therefrom through a pipe 185. The outlet chamber 182 is connected with the cylinder chamber 72 of the actuator cylinder 72 by a pipe 186 and the above-mentioned pipe 126.

The valve device 4% also comprises control valves 187 and 188 of which the valve 187 is an inlet or brake releasing valve for the brake mechanism and the valve 188 is a venting or brake applying valve for the brake mechanism. The valve 137 is carried by the diaphragms 183 and 13d and comprises a seat member 189 and a movable valve member 190 cooperating therewith. The seat member 189 is disposed around the fluid inlet end of a passage 191 of a screw-like member 192 which extends through the diaphragms 183 and 184. The passage 191 connects the inlet chamber 181 with the outlet chamber 132 in accordance with control movements of the valve member 191' and of the diaphragms 183 and 134, as will be presently explained. The valve member 1911 is mounted on a floating valve rod or common valve stem 1??? which extends through the passage 1% and into a co-operating relation with the valve 188.

The location of the diaphragm 183 in the housing 183 is such that it is subjected on one side thereof to the pressure of the inlet chamber 181'. The diaphragm 184 is located in the housing 189 so that it is subjected on one side thereof to the pressure of the outlet chamber 182. The adjacent sides of the diaphragms 183 and 1% are exposed to a vent chamber 1% which is normally in communication with the atmosphere through a vent passage 195.

The valve 188 comprises a valve member 197 mounted on the rod 113 and a valve seat 191% with which the valve member 1%? co-operates. Associated with the valve member 197 is a spring seat 199 which is engaged by one end of a valve spring 2%. This valve spring is disposed around the valve rod 196 and acts on the valve seat 18? in a direction to push the valve member 197 against its associated valve seat 198 and to also exert a pulling force, through the rod 193 on the valve member fit by which the latter is normally urged toward its associated valve seat 187.

The length of the valve rod 193 is such that a first flexing movement of the diaphragms 183 and 184 toward the left will assist the spring Ztlii in seating the valve member 197 against its valve seat 1%, and also such that further flexing of the diaphragms 183 and 134 toward the left after the seating of the valve member 197 will cause relative movement of the rod 1% in the passage 191 to open the valve member 190.

Flexing of the diaphragms 183 and 184 toward the left to cause such closing of the valve 188 and opening of the valve 187 will result from a predetermined pressure increase in the inlet chamber 181, such as will be produced in this chamber when the pressure of the brake pipe 179 is increased by fluid being introduced thereinto at the control vehicle. This flexing of the diaphragms 133 and 184 toward the left by an increase of pressure in the brake pipe 179 and in the inlet chamber 181 is resisted by a compression spring 2132; located in the outlet chamber 182 and which also acts to cause a return movement of the diaphragms 133 and 184 toward the right whenever the pressure in the brake pipe and in the inlet chamber 181 is decreased to a predetermined extent, such as by a brake pipe pressure reduction initiated at the control vehicle. Such a return movement of the diaphragms 133 and 15 i toward the right under the influence of the spring 2192 will cause closing of the valve member 191} against its seat 137 after which any continued movement of the diaphragms toward the right will cause the valve rod 1% to pull the valve member 197 away from its seat 198 and thus cause opening of the vent valve 138.

The valve seat 198 of the vent valve 188 is carried by a hollow screw-like stem 2133 which is adjustably mounted in the housing member by a threaded connection 2% therewith and whose axial passage 2135 forms a vent passage for venting the outlet chamber 182 to atmosphere whenever the valve member 197 is moved ofI" of its seat 198.

The spring 2192 is disposed in surrounding and coaxial relation to the valve rod 196 and has one end thereot engaged with a spring seat Zilti which is associated with the diaphragm 184 and mounted on the hollow valve stem. 192. The other end of the spring 2% is in engagement with a spring seat 2137 which is shiftable in the chamber 182 for varying the compression loading of the spring. The compresison of the spring 292 can be adjusted by means of suitable push pins 268 slidably mounted in openings 2&9 of the housing member 180 The inner ends of these push pins are in engagement with the shiftable spring seat 297 and the outer ends thereof are engaged by the transverse wall 211% of a nut-like cover 211 which has a threaded connection 212 with the housing member 18th. The vent passage 205 of the valve stem 203 is in communication with the atmosphere through an opening 213 of the cover 211.

From the construction above described for the compatibility valve 49 and the association of this valve device with other components of the brake mechanism 16, it will now be recognized that whenever the pressure of the brake pipe 179 is increased by fluid being introduced thereinto at the control vehicle to release the train brakes, such increased brake pipe pressure will be transmitted through the pipe 185 to the inlet chamber 181 and, acting on the diaphragm 183 in the manner explained above, will cause closing of the vent valve 138 and opening of the inlet valve 187. The opening of the inlet valve 187- will cause brake pipe pressure to be transmitted through the pipes 186 and 126 to the actuator cylinder '72 to cause a releasing actuation of the brake cylinder 71 in opposition to the brake applying spring ea. As long as the train brakes remain in a released condition, the brake pipe pressure will be maintained in the actuator cylinder 72 to hold the brake shoe 37 in its released position in opposition to the force of the spring 96.

When a brake pipe pressure reduction is made at the control vehicle for the purpose of applying the train brakes, the decrease in brake pipe pressure will result in a corresponding decrease in pressure in the inlet chamber 181 of the valve device 40 and'this, in turn, will cause closing of the inlet valve 187 and opening of the vent valve 188 in a manner already explained above. The

closing of the inlet valve 187 disconnects the actuator cylinder 72 from the brake pipe 179 and the opening of the vent valve 188 connects the actuator cylinder for venting to the atmosphere through the outlet chamber 182 and the vent passage 205. The venting of the actuator cylinder 72 permits the spring 96 to exert its expansive action against the cylinder head 82 and, through the brake beam 36, to cause the braking application of the shoe 37 in the manner already explained above.

The value relationship between the components of the valve device 40 is such that whenever the diaphragm means 183, 184 is in a stable or balanced condition with respect to the forces acting thereon, that is, the fluid pressures in the inlet and outlet chambers 181 and 182 and the force of the spring 202, the control valves 187 and 188 will be closed. On the other hand, when a condition exists in which the diaphragm means is willciently unbalanced, one or the other of the valves 187 and 188 will be opened, depending upon the direction of the diaphragm movement produced by the unbalanced condition. The exposed areas of the diaphragms 183 and 184 are appropriately selected and constitute a part of the valve relationship mentioned above.

The functioning of the valve device 46 is further illustrated by the diagram of Fig. 15 from which the advantages resulting from the use of the spring 202 in this valve device, as well as from the adjusting means for this spring, become apparent. In the Fig. 15 diagram, the broken-line curve 208 represents the variable pressure which would exist in the chamber 125 of the actuator cylinder 72 if fluid pressure were supplied to the latter cylinder from the brake pipe 179 directly instead of through the compatibility valve 40. The broken-line curve 209 correspondingly represents the variable brake releasing force which would be developed by the actuator cylinder 72.

The full-line curves 210 and 211 are similar to the curves 2% and 269 respectively in that they represent actuator cylinder pressure and brake releasing force but the considerably steeper slope of these full-line curves indicates the advantage achieved from the use of the valve device 40, and particularly, the important eflYect pro duced by the spring 202 which delays the supply of fluid pressure to the actuator cylinder until brake pipe pressure has increased to a desired value, in this case, to a pressure equal to or above approximately forty-two p.s.i. The adjustment for the loading of the spring 202 is important because it provides for calibration of the valve device 40 with respect to the normal brake pipe pressure of the particular type of train in which the vehicle 11 is to be used. Thus for freight train use of the vehicle 11, the loading of the spring 202 would be adjusted for a low brake pipe pressure, whereas, for passenger train use of the vehicle 11, the loading of this spring would be set for a higher brake pipe pressure. The adjustment of the loading of the spring 202 also adapts the valve device 49 for a particular portion of the pressure range of the brake pipe fluid being supplied.

The compatibility valve 40 can be located at any suitable point on the vehicle 11 and can be mounted on the selected vehicle portion, such as the portion 11. shown in Fig. 2, as by means of suitable attaching screws 215.

From the accompanying drawings and the foregoing detailed description it will now be readily understood that this invention has provided novel brake mechanism of a simple and reliable form and which will be suitable for use on vehicles of various kinds and particularly on vehicles of the convertible road-rail type. Since many of the features and advantages of this novel brake mechanism have already been explained in the foregoing specification, they need not be here repeated.

Although the brake mechanism of the present invention has been illustrated and described herein to a somewhat detailed extent, it will be understood, of course, that the invention is not to be regarded as being limited correspondingly in scope, but includes all changes and modifications coming within the terms of the claims hereof.

Having described our invention, we claim:

1. In brake mechanism for use with railway running gear comprising a rail wheel and a journal box having an axial shaft portion projecting therefrom; a brake beam; a brake cylinder carried by said beam; rod means operable in said brake cylinder and connected with said shaft portion; spring means in said brake cylinder in cooperation with said rod means and effective to supply brake applying force to said beam; a fluid pressure responsive cylinder device for supplying brake releasing force; and means for transmitting the brake releasing force from said cylinder device to said beam through said brake cylinder and in opposition to said spring means.

2. Brake mechanism for use with railway running gear which includes a rail wheel; comprising a brake beam having translatory brake-applying and brake-releasing movements; a brake shoe supported by said beam for braking co-operation with said wheel in response to the brake-applying translatory movement of said beam; a cylinder unit connected with said beam and comprising a brake cylinder and an actuator cylinder; rod means operable in said brake cylinder and anchored on said running gear; spring means in said brake cylinder and effective to impart said brake-applying translatory movement to said beam; a fluid pressure responsive piston means operable in said actuator cylinder for supplying brake releasing force; and lever means effective between said piston means and said brake cylinder for transmitting the brake releasing force to the latter in opposition to said spring means for producing the brakereleasing translatory movement of said beam.

3. Brake mechanism for use with railway running gear which includes a rail wheel; comprising a brake beam; a brake shoe supported by said beam for braking co-operation with said wheel; a cylinder unit containing a spring chamber and a pressure fluid chamber; rod means operable in said cylinder unit; said cylinder unit and rod means being operably connected between said running gear and brake beam; spring means in said spring chamber and expansively effective for supplying brake applying force to said beam; a fluid pressure responsive piston means operable in said fluid chamber for supplying brake releasing force in opposition to said spring means; and automatic slack adjusting means associated With said cylinder unit and rod means for automatically taking up slack to maintain the expansive movement of said spring means at a small value within which the brake applying force supplied by said spring means will be of a substantially constant value.

4. Brake mechanism for use with railway running gear which includes a rail wheel; comprising a brake beam; a brake shoe supported by said beam for braking co-operation with said wheel; a cylinder unit connected with said beam and comprising a brake cylinder and an actuator cylinder; rod means operable in said brake cylinder and anchored on said running gear; spring means in said brake cylinder and effective for supplying brake applying force to said beam; a fluid pressure responsive piston means operable in said actuator cylinder for supplying brake releasing force; lever means efl'ective between said piston means and said brake cylinder for transmitting the brake releasing force to the latter in opposition to said spring means; and slack adjusting means in said brake cylinder and automatically operable to vary the efiiective length of said rod means.

5. Brake mechanism for use with railway running gear which includes a rail wheel; comprising a brake beam; a brake shoe supported by said beam for braking co-operation with said wheel; a cylinder unit connected with said beam and comprising a brake cylinder and an actuator cylinder; rod means operable in said brake, cylinder and anchored on said running gear; spring means in said brake cylinder and effective for supplying brake applying force to said beam; a fluid pressure responsive piston means operable in said actuator cylinder for supplying brake releasing force; and a lever having a power input pivotal connection with said piston means and also having power output connections with said rod means and cylinder unit and located on the lever at different lever arm distances from said power input connection; said lever being effective to transmit brake releasing force from said piston means to said cylinder unit in opposition to said spring means.

6. Railway brake mechanism as defined in claim and wherein the power output connection of said lever with said rod means comprises fulcrum means carried by the latter.

7. Railway brake mechanism as defined in claim 5 and wherein said power input connection is at one end of said lever and the power output connection with said cylinder unit is at the other end; the connection of said lever with said rod means being at an intermediate point on said lever.

8. Railway brake mechanism as defined in claim 5 and wherein one of said power output connections comprises rockable thrust means effective between said lever and said cylinder unit.

9. Railway brake mechanism as defined in claim 5 and wherein the power output connection with said rod means is a pivotal connection by which said lever is supported and swingably fulcrumed on said rod means.

10. Railway brake mechanism as defined in claim 5 and wherein the power output connection with the cylinder unit comprises a second lever having one end thereof in a rockable thrust engagement with a seat located on said cylinder unit; and wherein said power input connection is located at one end of the first-mentioned lever and the other end of said first-mentioned lever is flexibly connected with the other end of said second lever.

11. Brake mechanism for use with railway running gear which includes a rail wheel; comprising a brake beam; a brake shoe supported by said beam for braking co-operation with said wheel; a cylinder unit connected with said beam and comprising a brake cylinder and an actuator cylinder; a piston rod operable in said brake cylinder and connected with said running gear; a spring seat on said piston rod; spring means in said brake cylinder in engagement with said seat and effective for supplying brake applying force to said beam; fulcrum means on said piston rod; a fluid pressure responsive piston means operable in said actuator cylinder for supplying brake releasing force; a lever swingable on said fulcrum means and having one end thereof connected with said piston means; and a rockable thrust means interposed between the other end of said lever and said cylinder unit for applying brake releasing force to the latter in opposition to said spring means.

12. Brake mechanism for use with railway running gear which includes a rail wheel; comprising a brake beam; a brake shoe supported by said beam for braking co-operation with said wheel; a cylinder unit connected with said beam and comprising a brake cylinder and an actuator cylinder; rod means operable in said brake cylinder and comprising a piston rod and a brake rod means coaxial with the piston rod and connected with said running gear; a spring seat on said piston rod; spring means in said brake cylinder in engagement with said seat and efiective for supplying brake applying force to said beam; slack adjusting means in said brake cylinder and automatically operable to vary the effective length of said brake rod means; fulcrum means on said piston rod; a fluid pressure responsive piston means operable in said actuator cylinder for supplying brake releasing force; a lever swingable on said fulcrum means and having a power input pivotal connection at one end thereof and connected with said piston means; and a rockable thrust means interposed between the other end 16 of said lever and said cylinder unit for applying brake releasing force to said cylinder unit in opposition to said spring means.

13. Brake mechanism as defined in claim 2 and which includes manually operable lever means connected with the first-mentioned lever for manually supplying the brake releasing force to the latter.

14. Brake mechanism for use with railway running gear which includes a rail wheel; comprising a brake beam; a brake shoe supported by said beam for braking co-operation with said wheel; a cylinder unit connected with said beam and comprising a brake cylinder and an actuator cylinder; a piston rod operable in said brake cylinder and connected with said running gear; a spring seat on said piston rod; spring means in said brake cylinder in engagement with said seat and effective for supplying brake applying force to said beam; a fluid pres sure responsive piston means operable in said actuator cylinder for supplying brake releasing force; lever means effective between said piston means and said cylinder unit for transmitting the brake releasing force to the latter in opposition to said spring means; roller means on said cylinder unit; and a manually operable brake release lever having a pivotal actuating connection with said lever means and a cam portion for co-operable thrust engagement with said roller means.

15. Brake mechanism as defined in claim 14 and wherein said cam portion includes a detent means for co-operation with said roller means for releasably holding said manually operable lever in a brake-released position.

16. Brake mechanism as defined in claim 14 in which said cam portion includes a detent means for co-operation with said roller means for releasably holding said manually operable lever in a brake-released position; and wherein torsion spring means effective on said release lever causes release of said detent means from said roller means in response to a fluid pressure actuation of said piston means.

17. In railway brake mechanism; a brake cylinder device comprising a brake cylinder and a hollow piston rod operable therein; a spring seat on said piston rod; spring means in said cylinder and expansively effective between said seat and cylinder for supplying brake applying force; brake rod means projecting from said cylinder and subject to pushing and pulling forces and com prising co-operating screw and nut members in said piston rod; and slack adjusting means responsive to said pushing and pulling forces for automatically producing relative rotation between said screw and nut member for varying the length of said brake rod means.

18. A brake cylinder device comprising a cylinder; rod means operable in said cylinder and projecting therefrom; said rod means comprising a piston rod having a spring seat thereon, and co-operating screw and nut members coaxial with said piston rod and being relatively rotatable for varying the effective length of said rod means; spring means in said cylinder in engagement with said seat and effective for supplying brake applying force; said nut member having helical cam means thereon; reaction means co-operating with said cam means for causing rotation of said nut member in re sponse to axial forces on the rod means for varying the effective length of said rod means; and detent-type releasable holding means acting between said cylinder 7 members coaxial with said piston rod and being relatively rotatable for varying the effective length of said rod means; spring means in said cylinder in engagement with said seat and eifective for supplying brake applying force; said nut member having helical cam means thereon; a reaction member connected with said cylinder; roller means co-operating with said cam means for causing rotation of said nut member in response to axial forces on the rod means for varying the effective length of said rod means; and mounting means rotatably and rockably mounting said roller means on said reaction member.

20. In brake mechanism for a vehicle having a brake pipe which during normal use of the vehicle is charged with fluid pressure of a pressure value above atmospheric pressure, a brake cylinder device comprising a spring cylinder and an actuator cylinder, rod means operable in said spring cylinder and including a spring seat, spring means in said spring cylinder in engagement with said seat and effective for supplying brake applying iiorce, fluid pressure responsive piston means movable in said actuator cylinder and operably associated with said rod means and spring cylinder for supplying brake releasing force in opposition to said spring means, and a valve device communicatively connecting said actuator cylinder with said brake pipe for automatically supplying pressure fluid to and venting the same from said actuator cylinder in response to predetermined brake pipe pressure variations, said valve device comprising a first control valve means operable to supply pressure fluid to said actuator cylinder in response to a predetermined brake pipe pressure increase and other control valve means operable to vent said actuator cylinder to atmosphere in response to a predetermined brake pipe pressure reduction.

21. In brake mechanism for a vehicle having a brake pipe which during normal use of the vehicle is charged with fluid pressure of a pressure value above atmospheric pressure, a brake cylinder device containing a spring chamber and a pressure fluid chamber, rod means movable in said cylinder device and carrying a spring seat, spring means in said spring chamber in engagement with said seat and eifective for supplying brake applying force, piston means responsive to the fluid chamber pressure and connected with said rod means for supplying brake releasing force in opposition to said spring means, and a valve device communicatively connecting the fluid chamber with said brake pipe for automatically supplying pressure fluid to and venting the same from said fluid chamber in response to predetermined brake pipe pressure variations, said valve device comprising a first control valve means operable to supply pressure fluid to said fluid chamber in response to a predetermined brake pipe pressure increase and other control valve means operable to vent said fluid chamber to atmosphere in response to a predetermined brake pipe pressure reduction.

22. In brake mechanism for a vehicle having a brake pipe, a brake cylinder device containing a spring chamher and a pressure fluid chamber, rod means movable in said cylinder device and carrying a spring seat, spring means in said spring chamber in engagement with said seat and effective for supplying brake applying force, piston means responsive to the fluid chamber pressure and connected with said rod means for supplying brake releasing force in opposition to said spring means, and a valve device communicatively connecting the fluid chamber with said brake pipe for automatically supplying pressure fluid to and venting the same from said fluid chamber in response to predetermined brake pipe pressure variations, said valve device comprising a housing containing an inlet chamber connected with said brake pipe and an outlet chamber connected with said fluid chamber, said housing also having a vent passage for venting said outlet chamber to atmosphere, diaphragm means in said housing between said inlet and outlet chambers and responsive to the pressure differential of the fluid pressures in said inlet and outlet chambers, other spring means in said outlet chamber and effective against said diaphragm means in opposition to the fluid pressure in said inlet chamber, a first control valve means providing controlled communication between said inlet chamber and said outlet chamber, and a second control valve means controlling said vent passage, said first and second control valve means being responsive to movements of said diaphragm means.

23. Brake mechanism as defined in claim 22 and wherein said first and second control valve means comprise movable valve members carried by a movable common valve stem extending through said diaphragm means.

24. Brake mechanism as defined in claim 22 and wherein said valve device also comprises adjusting means for varying the effectiveness of said other spring means.

25. Brake mechanism as defined in claim 22 arid wherein the diaphragm means of said valve device comprises a pair of spaced diaphragms, the space between said diaphragms being connected with atmosphere through a normally open vent passage.

References Cited in the file of this patent UNITED STATES PATENTS 601,872. Fraser Apr. 5, 1898 1,466,452 Lipcot et a1. Aug. 28, 1923 2,096,463 Moody Oct. 19, 1937 2,109,871 Thode Mar. 1, 1938 2,295,196 Barr Sept. 8, 1942 2,311,842 Larson Feb. 23, 1943 2,504,712 Mann Apr. 18, 1950 FOREIGN PATENTS 2,660 Great Britain of 1877 448,153 Great Britain June 3, 1936 

